Dongguan Zhongen PC/ABS 5007BK is a black-pigmented polycarbonate/acrylonitrile-butadiene-styrene alloy supplied as pelletised feedstock for injection moulded components requiring low-temperature ductility, dimensional stability and moderate thermal resistance. The material is processed on standard reciprocating-screw injection moulding machines with clamp force between 800 kN and 12,000 kN. Pre-drying in dehumidified-air equipment is mandatory: pellets are held at 100 °C for 4 h until residual moisture is below 0.02 wt%. Transfer systems exposed to ambient air at more than 60% relative humidity for more than 30 min can reintroduce surface moisture, and in high-humidity mould shops an insulated hopper with a dew point below -30 °C is required. A starting barrel profile of 240 °C to 270 °C is typical for unfilled PC/ABS, with nozzle temperature held at 255 °C to 265 °C. Because the black pigment package contains carbon black, the melt shows a measurable increase in low-shear viscosity compared with unpigmented PC/ABS; comparative melt-mass flow rate testing at 260 °C and 5 kg under ISO 1133-1:2022 records a 5% to 15% lower value. Published data for this specific configuration is limited; processors should not substitute these values for a grade-specific certificate of analysis.

In a 2.0 mm wall-thickness electronic housing moulded on a 120-ton hydraulic injection moulding machine with a 40 mm general-purpose screw of 20:1 L/D ratio and 2.5:1 compression ratio, the practical melt-temperature window is constrained to 245 °C to 275 °C. Gate-area delamination and surface splay are observed when the melt is held above 270 °C for more than 5 min; at the lower boundary, short shots and poor weld-line filling occur below 245 °C. Screw rotation speed is maintained at 60 rpm to 120 rpm, and back pressure is set between 5 bar and 15 bar. Increasing back pressure above 20 bar does not improve pigment dispersion but increases shear heating and may cause carbon-black agglomeration at the check ring. Injection speed should be profiled to fill the cavity in 1.5 s to 2.5 s; hold pressure is then applied at 50% to 70% of peak injection pressure for 8 s to 12 s to minimise sink marks at bosses and snap-fit features.

Moisture analysis should be performed by Karl Fischer titration or a calibrated moisture analyser with 0.005 wt% resolution. The 0.02 wt% limit is slightly lower than the generic PC/ABS recommendation because carbon black can adsorb moisture at the pellet surface and increase splay at vent locations. In one production scenario, a hopper drier setpoint of 90 °C instead of 100 °C produced intermittent splay due to residual moisture above 0.03 wt%. Increasing the setpoint to 100 °C and extending residence in the hopper to 4 h eliminated the defect. This equipment-level result is not a certificate of analysis; it indicates the sensitivity of black-pigmented PC/ABS to incomplete drying.

What separates a black-pigmented PC/ABS grade from unpigmented PC/ABS in injection moulding?

The main measurable difference arises from carbon black particle dispersion and its effect on weld-line integrity. Carbon black at loadings from 0.2 wt% to 1.0 wt% does not alter tensile yield stress significantly, but it can reduce notched Izod impact measured at 23 °C under ASTM D256-23 by 10% to 30% when the weld line is located in the impact region. Tensile yield stress of unfilled PC/ABS is typically 50 MPa to 60 MPa under ASTM D638-14 at 50 mm/min; flexural modulus ranges from 2200 MPa to 2600 MPa under ASTM D790-17. A black grade that shows a drop in melt-mass flow rate below 8 g/10 min at 260 °C and 5 kg should be investigated for over-drying or for excessive fines generated by pellet conveying, because such viscosity shifts are not characteristic of the base PC/ABS. The pigment also masks yellowing caused by thermal-oxidative degradation; therefore processors cannot use colour change as an early warning of polymer breakdown.

Rotational rheometry of carbon-black-filled PC/ABS typically shows a higher storage modulus in the terminal zone than the unpigmented control. At angular frequency 0.1 rad/s and 260 °C, the filled material can display a complex viscosity plateau that is 20% to 40% higher. This has implications for hot-runner pressure drop: for a hot-runner system with 6 mm diameter channels, the observed pressure drop can rise from 180 bar to 240 bar at 30 cm³/s volumetric flow when carbon black is introduced. These values are not grade-specific for 5007BK but are drawn from reported comparative studies of pigmented and unpigmented PC/ABS formulations.

Thermal performance of unfilled PC/ABS is normally reported with heat deflection temperature from 95 °C to 110 °C under ASTM D648-18 at 1.8 MPa, and Vicat softening temperature from 118 °C to 132 °C under ISO 306:2013 method B50. These values are family ranges, not certified values for 5007BK. Continuous surface temperatures above 85 °C can produce creep and loss of screw torque retention in service. For short-term exposure, the material may tolerate 110 °C peak temperatures, but the permissible time depends on part geometry and applied stress; published data for this specific configuration is limited.

When barrel residence time exceeds 6 min

At melt temperatures above 260 °C, the butadiene component of the ABS phase undergoes thermal crosslinking and the polycarbonate phase undergoes chain scission. In dark-pigmented material the brown degradation products are not visible, but the loss of notched Izod impact under ASTM D256-23 can exceed 40% after 8 min residence at 270 °C. Mould deposit on vent pins and core slides increases with repeated cycles, and the deposit can then transfer to the part surface. A production-scale observation on a 200-ton machine running a two-cavity automotive bracket mould showed that limiting barrel residence to 4 min to 5 min reduced pin deposition and stabilised weld-line impact. Processors should interrupt production at 6 min by purging with unpigmented PC/ABS or with a dedicated purging compound, then reduce barrel temperature to 180 °C if the machine is idle for more than 15 min. A high-shear screw with compression ratio 3.5:1 can raise melt temperature by 10 °C to 15 °C above barrel setpoint; therefore setpoints above 255 °C should be evaluated with a needle pyrometer before production approval.

Dongguan Zhongen PC/ABS 5007BK is typically positioned for electrical enclosures, automotive interior brackets, appliance structural parts and medical device housings where a stable black surface and moderate impact performance are required. In electrical enclosures, the grade may be acceptable for UL 94 HB when the wall thickness is at least 1.5 mm; it must not be assumed to meet UL 94 V0 unless a yellow-card listing for this specific grade is provided. In automotive interior use, the grade is generally limited to parts not continuously exposed to fuel, brake fluid or aromatic solvents, because PC/ABS is susceptible to environmental stress cracking. In medical housing applications, biocompatibility data for the final sterilised part are required because the pigment and processing aids are not automatically covered by generic polymer statements. Published data for this specific configuration is limited for radiation sterilisation compatibility above 25 kGy.

Compared with neat ABS, PC/ABS 5007BK requires higher drying temperature and longer drying time because the polycarbonate phase hydrolyses at melt temperatures if residual moisture exceeds 0.02 wt%. Neat ABS is often dried at 80 °C for 2 h, while PC/ABS requires 100 °C for 4 h. Compared with neat polycarbonate, the blend has lower melt viscosity and improved thick-section notched impact under ASTM D256-23, but lower transparency and higher susceptibility to hydrocarbon-induced stress cracking. The alloy is therefore selected when the part design includes snap-fits and bosses that would crack in neat polycarbonate due to notch sensitivity, but not when optical clarity is required.

Compared with PC/PBT, PC/ABS 5007BK has higher low-temperature impact and lower mould shrinkage, but lower resistance to continuous contact with lubricants and fuels. PC/PBT is selected when the part must withstand 1000 h of hot-air ageing at 120 °C or continuous exposure to engine oil. Compared with PC/ASA, the PC/ABS alloy has higher tensile yield stress and lower raw material cost, but PC/ASA retains gloss and colour better under ISO 4892-2:2013 xenon-arc weathering. Compared with mineral-filled PC/ABS, the unfilled 5007BK has lower flexural modulus but higher weld-line strength and lower moulded-in surface roughness. Compared with glass-filled PC/ABS, it has significantly lower modulus and dimensional stability under heat, but avoids the anisotropic warpage that glass fibre orientation introduces.

Dimensional stability of moulded parts depends on mould temperature. Mould surface temperature should be held between 60 °C and 90 °C. At mould temperatures below 60 °C, PC/ABS skins freeze before adequate packing, increasing sink marks at ribs and bosses; above 90 °C, cycle time increases and ejection marks can form on unreinforced parts. The use of sequential valve gates or multi-point gating reduces weld-line visibility, but each additional gate creates a lower-impact-strength weld plane. For automotive interior trim with visible grained surfaces, chemical foaming agents are sometimes used, but they can reduce weld-line strength by a further 15% to 25% compared with compact mouldings. Published data for this specific configuration is limited; mould-flow simulation with actual weld-line models is required to verify performance.

For laser-marking contrast and laser welding, carbon black presents a specific limitation. Standard carbon black absorbs near-infrared radiation and prevents laser transmission; therefore PC/ABS 5007BK is generally unsuitable for laser transmission welding. If dark-coloured parts require laser welding, a laser-transparent black pigment based on mixed metal oxides or organic dyes must be specified instead. For aesthetic consistency, colour matching between lots should be controlled under ISO 3664:2009 lighting conditions because carbon black opacity can mask gloss differences.

Regulatory compliance must be confirmed with the supplier for each production lot. The black pigment and processing aids are part of the formulation and may influence extractables or heavy-metal reporting. The verification matrix below lists the minimum documentation that should be requested for electrical, automotive or medical applications.

For applications requiring UL 94 V0 at wall thickness below 1.0 mm, for laser transmission welding, or for continuous outdoor exposure without painting, published data for this specific configuration is limited. The supplier documentation for Dongguan Zhongen PC/ABS 5007BK should be reviewed for the exact melt flow rate, tensile and impact values, and regulatory certificates before specification.